Device for regulating the terminal voltage of generators



Oct. 14, 1930. N. A. J. VOORHOEVE ET AL 1,7

DEVICE FOR REGULATING THE TERMINAL VOLTAGE OF GENERATORS Filed Dec. 19,1927 and JTG.,Defi'ams,

Patented Oct. 14, 1930 UNITED STATES PATENT OFFICE NIGOLAAS ANTHONYJOHANNES VOORI-IOEVE AND JOHAN CHRISTIAAN DE HAAS,

OF EIND'HOVEN, NETHERLANDS, ASSIGNORS TO N. V. PHILIPS GLOEILAMPENFAB-RIEKEN, OF EINDHOVEN, NETHERLANDS, A LIMITED LIABILITY COMPANY OF THENETHERLANDS DEVICE FOR REGULATING THE TERMINAL VOLTAGE OF GENERATORSApplication filed December 19, 1927, Serial No. 241,212, and in theNetherlands April 12, 1927.

This invention relates to an improvement in or modification of acompounding device for regulating the terminal voltage of a generator.Such a compounding device which permits to effectuate an overcompoundregulation or a regulation at a constant terminal voltage, has thedisadvantage inherent in the majority of these devices that in the caseof the working-circuit being short-circuited the evil is aggravatedinstead of being remedied. Therefore, with such regulating devices, forexample, with the so-called mechanical regulators, it is customary touse, in addition to the regulator proper, a special device which,

in the case of short-circuits, serves to limit the short-circuitcurrent.

The invention relates more specifically to a device of the above saidclass, in which the exciting current of the generator is influenced bymeans of one or more incandescent cathode discharge tubes connected inparallel with the exciting winding, the heating current of which isregulated in dependency of the main current or of the terminal voltageof the generator by generating in the heating circuit a tension which isdependent of that main current or of that terminal voltage of thegenerator and which amplifies or weakens a second tension generated inthe same circuit substantially independently of the main current or ofthe terminal voltage.

According to the present invention both above-mentioned tensions are soadjusted relatively to each other that in casethe generator is loadedthe plate current of the discharge tubes falls OH to zero and increasesagain when the load further increases.

The invention will be more clearly understood by referring to theaccompanying drawing which represents, by way of example, an embodimentof the invention, said drawing being a circuit diagram of the elementsinvolved in the invention.

Referring to the figure, 1 denotes the armature of the generator to beregulated, 2 is the exciting winding which may be connected across acurrent-limiting resistance 6 to a suitable source of tension. Inparallel to the said exciting winding is connected a so-called diode-3the anode and the cathode of which are indicated by 4 and 5respectively, a resistance 8 being included in the load current circuit.The heating circuit of the tube 3 comprises a source of tension 7, whichin the drawing is a direct current battery. The load current flowsthrough the resistance 8. The voltage drop 6 produced in the saidresistance will rise with an increasing load-current. If

the regulation according to the invention had not been provided, theterminal voltage would decrease with an increasing load-current.

Let the tension 6 be opposed to the tension E generated by the battery7. When the tension 6 increases, the heating current of the diode willdecrease, as a result of which the internal resistance of the diodebecomes larger owing to which the exciting current flowing through thewinding 2 increases. Due to this increase the terminal voltage of thegenerator rises to such an extent that with a regulation at a constantterminal voltage the initial decrease is neutralized thereby.Consequently, from no-load to full-load a substantially constantterminal voltage of the generator will be obtained in that case.

In the case of overloading, the device is so adjusted that the tension 6is substantially equal and contrary to the tension E, the latter beingconsequently neutralized. As a result, the filament 5 will emit nolonger and the internal resistance of the tube 3 becomes so large thatno current can flow through the diode. If overloading occurs theterminal voltage of the generator will, consequently, have a normalcourse, in other words: a course as if no compounding device werepresent.

In the case of a short-circuit, the generator current will increasestrongly and a great loss of voltage will occur in the resistance 8.This loss of voltage will predominate over the tension E generated bythe battery 7. Therefore, in the heating circuit will flow again acurrent which causes the diode to function, owing to which the excitingcurrent considerably decreases. Due to the strong increase of theheating current the terminal voltage shows an abnormally abruptlydrooping course, the short-circuit current being consequently limited.

What we claim is:

In a device for regulating the terminal voltage of a generator, adischarge tube connected in parallel with the exciting winding of thegenertor and constituting means for controlling the excitation of thegenerator, a circuit including means for regulating the supply ofheating current to said tube, in consonance with the main current of thegenerator, said means establishing, in the heating circuit, a

tension dependent upon that of the main current, means for generating.another tension in the second mentioned circuit substantiallyindependent of the main current,- arid means whereby both tensions maybe Varied relative to each other, and whereby, in the event thegenerator is loaded, the plate current of the discharge tube will bedecreased to zero and be increased, again, upon further increase of theload.

In testimony whereof we afiix our signatures, at the city of Eindhoven,this 26th day of November, 1927.

NICOLAAS ANTHONY JOHANNES VOORHOEVE. JOHAN CHRISTIAAN de HAAS.

